US1614025A - Composition of matter derived from black liquor and process of dealing with the same - Google Patents

Description

Patented Jan. 11,1927.

UNITED STATES 'cnusnrrs, 'musrnns.

PATENT OFFICE.

MALDEN, MASSACHUSETTS, ASSIGNOR T ALFRED S. WILLIAMS, 'OF BOSTON, MASSACHUSETTS, AND JOHN T. COLLINS, OF SANDWICH, MASSA- comroslrron or a umna DERIVED mom ZBLACK LIQUOR AND rnocnss or DEALING WITH THE SAME. i

No Drawing.

This invention relates to compositions of matter obtainable from the spent or black liquor of the chemical wood pulp-industry,

and the art of producing molded. solid artiwaste liquid resulting in the digestion of chemical substances. I understood nature {but they are for the most,

wood in the soda process and in the sulfate process. of making pulp for paper. Although it represents about one-half the weight of the wood, it finds no direct use in the arts; and efforts heretofore made to 'discover uses for it or to recover values known to be in it have proved unavailing, except as to the alkali. Therefore the black liquor is generally evaporated until it becomes thick, and the'nis burned in order to regain'its contained alkali.- Itis an object of the present invention to discover ways to utilize this hitherto wasted material. The black liquor is thought to comprise very many difierent These are not of well part something called lignin, which is a sort of group name for the noncellulose constituents of wood fibre: and the coniferous woods towhich the soda and sulfate processes are usually applied have also various Y resinous bodies. Normally insoluble in plain water, all of these substances are however taken up by the caustic soda solution used in the said process; and theyv are accompanied by awide variety of water-soluble materials of subordinate importance, acetic acid, sugars, soluble carbohydrates, etc.

By the invention the black liquor is treated chemically so as to produce a material which is herein, for convenience, referred to by thegenericrterm of wood gum; and this I have found capable of manipulation I by physical, chemical and/or physico 'chemical processes to'make derivative compositions of matter that are. capable of being i molded by heat and pressure into hard and sniooth forms whiehare insoluble and are 'sufiiciently tough and permanent to have a wide range of utility'in th e industrial arts. A crude, and more or less impure, form of the wood gum is obtainable from. the black liquor by a simple process of precipitation by adding acid, as for example, sulfuric acid. In the case of pine this is a fusible,

clry, dark brown powder, which "cannot be Application med August,

1924. Serial No; 732,114.

dissolved in water and..is only about soluble in methyl alcohol or in benzol. While this gum can beused for many purposes, it is preferred to work with a purified. form vhich may be obtained bywashing the crude wood gum to free it of salines and other water-soluble substances and then dissolving it in a suitable alkaline liquid, as for example caustic soda or ammonia; filtering to get rid of occasional fibres which are visible to the eye in the crudegum, and other impurities; and then adding acid to the filtered liquid, whereupon the purified form is obtained as a precipitate. be used as a molding composition in this form or in combination. Thus, itmay ,be

mixed with glue and the glue hardened with formaldehyde.

erties and because of its intimate mixture with the hardened glue. In a somewhat The wood gum may similar manner the wood gum in powdered form may be mixed with shellac; and when' both have been softened by heat they together assume the shape of the mold, and cool as a solid mass in the molded shape.

the gum alone can be molded without any added binder such as glue or shellac. After being softened or fused by heat in the mold it hardens nto a black, firm molded article. y As regards the glue and the shellac, I have not observed that any chemical reaction occurs between either of them and the wood gum; but the wood gum may be made to react chemically, as with formaldehyde. .In this case the formaldehyde disappears, and'a new.

compound results which appears to. be only slightly fusible when heated in the open air,

but which can be fused by heat and ressure when secluded, as in a mold, an which hardens into a resistant solid. A product which can be similarly molded is obtainable by combining the wood gum with phenol, as adding cresylic acid to the black liquor or a purified form thereof, and treating with acetaldehyde. In this case a vigorous reaction occurs with spontaneous heat.- This being over, the product is neutralized with.

acid, and a viscous mass in the nature of a condensation product separates, which being washed and dried can be ground fine making a darkbrown powder, easily fusible. This can be then softened in a mold, under heat and pressure, from which state it solidifiesinto a molded article which is not easily fusible or soluble, if at all. Also a condensation product may be made from the combination of the wood gum and phenol on the one part with formaldehyde on the otherpart, upon which. a reaction follows producing a light brown condensation product which differs from the Well known phenol-formaldehyde condensation product, but which c an be moldedunder heat and pressure, solidifying into a black molded article which is strongly cohesive, hard, durable and-resistant. Considering this as a co-condensation' product, inasmuch as the caustic soda which keeps the wood gum in solution also dissolves pther organic bodies, including phenols, it illustrates how to effect co-condensation of the wood gum or liquid with such other orgamc bodies, affordin a variety of new and useful products. hese products are useful for the plastic arts where wood gum and phenols are in alkaline solution, and the cocondensation is effected with the aid of formaldehyde, but the properties of the co-condensed products are not merely the suniof the properties of the two materials separate- 1 condensed with formaldehyde; nor are they the properties of either alone. They, however, have the hardness of the black liquor products without their brittleness.

While the wood gum has been mentioned as one of the initial ingredients in the above sketch of the invention, it is possible to omit the stage of precipitating this gum, and to apply the process of the invention directly to the black liquor, either in crude or in purified form. By thus eliminating much of the labor and the time for drying and grinding the powder the cost of the process is very greatly reduced, belowits already low figure. Moreover, it is found that in making the ultimate molded article a filler of suitable sort may usually be employed withadvantage, such as wood flour, while retaining or even increasing the cohesive strength of the ultimate product. Other aldehydes may be used, for example,- furfural. And in lieu of the cresylic acid mentioned, any other convenient phenol may be used, as the various wood creosotes, coal tar creosotes, tarry phenols, etc.

It will thus be seen that'the invention can be-produced with various materials and with considerable variation in the steps employed."

Fundamentally the invention is concerned with certain of the dissolved matters of the black liquor which by the invention are capable of conversion into various substances useful for plastics. Such derivative substances may be obtained either immediately by acid precipitation or less proximately by a process involving further chemical reaction; and they may be utilized either per se, or in admixture with a known binder such as shellac or glue, by. a molding and baking process, or by further change into a chemical compound in which an aldehyde first reacts with it to produce a partial condensation product whose complete hardening occurs after the product at this stage has been arranged in a mold with suitable filler and has been then subjected to heat and pressure. The wood gum by itself, as derived directly from the black liquor, is also useful as an antiseptic, and for other purposes.

The invention thus opens a large new fieldin the industrial arts, based on the processes which can be carried out and the useful articles which can be made from the materials which have hitherto been wasted in the black liquor. It is intended that the patent shall cover by suitable expression in the appended claims, whatever'features of patentable novelty exist in the invention disclosed.

Illustrative examples of theinvention,

showing the manner and process of making,

constructing and compounding and using it will now be given in greater detail. In order paring pulp for the manufacture of paper,

may be. acidified. The customary evaporation process of this liquor may be omitted, and the acidification carried out with sulfuric acid, which is preferred because of its low cost, although probably any other aci may be used. Therebv a precipitate is formed, which is black. leaving a practically colorless liquid. This being poured off, the precipitate which is mainly made up of derivatives of the wood that are normally in solube in water. presumably including the group of substances'cal'led lignin, and resinacids. etc.. may be manipulated, or broken tine and washed with water. thus removing such water-soluble solids and such liquids,

acetic acid. sugars, etc. as did not gorwith the liquid but remain in or with the precipitate: and the washed precipitate mav then be dried, particularly if it. is to be used in this form as a. molding compound. If

mixture with other ingredients as glue,

acid (99%, strawcolor);

or to aid the uniformity of its shellac, wood flour, in molding. If, however, the wood gum is to be treated further chemically, this drying step would not be 'nece'sthe drying sary 'incommercial operation. In either" event it is next dissolved in a caustic soda solution.

may take300 grams of washed and dried,

For an. illustrative example one precipitated material and dissolvethat in a solution of 1000 grams of water and I00 grams of caustic soda, the important feature being to have suflicient of the caustic soda to dissolve all of the gum. To that mixture may be added 300 grams of crude cresylic and to-that 600 grams of formaldehyde, 40% solution. a The mixture being then heated, for example to 50 (1, a reaction occurs; after which the.

whole is allowed to cool: and then it is to bev neutralized, for which purpose I have found nitre-cake or sodium acid sulfate, NaHSO,, serviceable, although other acids might beused, whereupon a viscous mass like putty separates. This mass, which is not sticky, may be washed with water and spread out to dry in the open air, by which process its viscous nature departs. and it can be ground. Being then thoroughly washed and dried, it appears as a light brown powder. This condensation product is fusible and is used to make the finished molded compound preferably by thoroughly mixing with a I filler such as wood flour, for which compound I have taken the condensation product and the filler in about equal proportions. This powder mixtiire being .poured into a mold, to which pressure and heat are applied, as, for example.about 150 C. and 3000 pounds, the mass softens, molds and after a few minutes under heat is completely set, producing a smooth, black, strong article.

In place of the formaldehyde one may use acetaldehyde with successful results. The reaction is somewhat more violent. For the molding of a composition of,5( parts of this condensation product and 50 parts wood flour, hexametliylenetetramine may be added a to the extent. of 20 parts. for its hardening efl'ect although hardening is not necessary.

.This mixture being heated to.160 C. and compressed for a few minutes the molded product results. The acetaldehyde condensation product thus used is obtained as follows:

60 grams of the precipitated wood gum above described being dissolved in a solution composed of 20 grams of caustic soda and 200 c. c. of water, boiled together until the gum is clearlydissolved, cresylic acid is added and the entire mixture is co'oled to room temperature. Acetaldehyde' now being added, a vigorous reaction takes place with spontane ous heat. A separation occurs of two layers,- one dark and l quid like the original 'black liquor and the other light yellowish and small in amount. The whole is allowed to stand, until the reaction is completed, and. then iswarmed to 7 5 (1., and let stand an hour: and 43 e. e. of 50% sulfuric acid being 0 Heat is noticed from the addition of the form-.

aldehyde, the (haracteristic order of which continued in-the mixture. But'upon warming to 80 C. and allowing to, stand an hour cooling, the odor of formaldehyde is found to be gone. and the odor is of an alkaline nature, similar to that of the original black liquor. From this, with 13.5 c. c. of 50% sulfuric acid a precipitate is made which is nearly black (very dark brown) having a burned sugar odor. The mixture may become so thick that itcan be stirred only with difficulty; in which case it may be advisable to add water for thinning it. In one instance 186 c. c. of water having been thus added, andthe product being filtered, washed and '1 hen dried, it was found to have a weight of 53 grams. Some of the particles'appear to have a vitreous fracture, but the product is not fusible in the open air, decomposing instead ata high heat, with flame. This condensation product is clearly something different from the original gum, because in addition to the above noted disappearance'of formaldehyde, quickly when the temperature was raised and with a'reaction proceeding rapidly, it is also observed that whereas the gum upon being heated can be molded together into a ball. this condensation product under the same conditions is not suiticiently. adhesive to do this, but simply burns. When this condensation product is molded with an equal amount of wood flour added, and with formaldehyde, but without any addition of phenol, it is observed that the material seems to set more quickly than when the phenol has been added. As in the other cases, article molded from this have satisfactory strength and aspect.

Instead of going throughthe preliminary step above described of obtaining a solid wood gun from the black liquor, the wood condensation product may be obtained from 3 the black liquor direct. even without preliminary purification. although with slightly different results as follows: The black liquor being preferably concentrated to half its added, a viscous mass separates, as in the volume, by evaporation, the desired amounts of phenol and formaldehyde are added, and the mixture is heated to 80 0.; and then after standing an hour or so is precipitated with sulfuric acid, giving a yield considerably greater in weight than the ordinary yield .for the process which has been deabove.

scribed with the solid wood gun. 'This condensation product diifers also in that it does not come out in the plastic form, but is granular, which makes it easier to handle; and the powder is very light in color, with no characteristic whatever of sticking together. This can be dried in a very short time into brittle form for fine grinding,

without the long and relatively difficult drying characteristic of the product described The molded product, made from equal amounts of this and wood flour, re-

sembles the previously described molded may be variations from these proportions in practice and for this purpose a preliminary test of the qualities of the black liquor may be made by precipitation, filtering, washing,

' drying and weighing a sample quantity, to

find how much wood gum material there is in the particular black liquor that 18 at hand and at the particular degree of conc'entra tion which it happens to have. In one example it was found that 1 000 c. c. of black liquor was the equivalent of 40 grams of wood gum. to which was added 40 grams of phenol and 80 grams of formaldehyde, the caustic soda being already in the solution.

'In this particular case the precipitation of the condensation product was effected by 30 c. c. of 50% sulfuric acid, from which there came a yield of 140 grams of condensation product. Contrasting this with the combined weight of wood gum and cresylic acid or phenol (80 grams), this indicates that certain materials in the black liquor which are lost by the above described purification processes are saved and utilized by this method of making the black liquor itself an. ingredient for gettting the condensation product. I

The temperature above stated for the various stages of reaction are not definitive in the sense that the process of the invention cannot be carried out at other temperatures. For example, although 50 C. has beenmentionedas a suitable temperaof brown, but upon placing in the mold,

heating and pressing as above'dcscribed a fusion or equivalent rearrangement occurs, and a hard, smooth satisfactorily molded article results.

For cases where a molded article is to be made from the wood gum direct with aid of glue, one may take 10 parts of wood gum, 10 parts of wood flour or other filler, 4 parts of glue and 1 part of hexamethylenetetramine. The glue may be ordinary glue of commerceof animal origin and if desired may be less in proportion than above specified, e. g. 2 parts of glue. The hexamethylenetetramine if desired may be taken in greater proportion, allowing the above to react on the glue as a hardener, and allowing as much more to react on the wood gum. The ingredients may be mixed cold, put into the mold, and pressed hot, e. g. at about 40 C.- for a few minutes.

In any of these cases the} pressure used may be only that needed to carry out the molding operation satisfactorily. Incases where a form of the invention is used whichfuses in open air, it appears that articles can be cast from it, without pressure; but the use of pressure between dies is both a quick and an inexpensive method 'of proce dure, andit has the advantage of excluding air so as to'prevent the occurrence of any combustion. e

Inmaking the condensation product of wood gum, phenol and formaldehyde above described, any convenient commercial phenolic material may be used. No catalyst is required to carry through this or any other process herein described. The acid ifying is preferably done slowly, and any acid can be used, even products of combustion. The precipitate comprising the condensation product separates as a gray solid; but the color changes to brown upon standing in air. The grinding or comminuting step is to' aid the thoroughness of the washing which follows: and also tdput the material into. form best suited for molding. The processes above defined-are as performed with-an ordinary screw press, in which the. dies are'first heated to the desired degree, but the pressure of 3000 pounds estimated, in these instances is not required for successful operation; and the tempera-v ture also may be varied. The product becomes hard in a few minutes in the mold. It will be observed that in each case the process is very simple, in that the materials can flow in cold, in powdered form, and the process iscompleted by a sort of'baking.

The invention .has thus been set forth so that anyone can practice it without need to determine the exact chemical nature of certain materials, especially the wood gum and the condensation products to which it contributes, because the exact nature of some of these may prove a diflicult chemical problem, about which opinions may differ. One may say, however, that when the black liquor comes from coniferous woods, which are likely to afford the greatest field for utility of the invention, the wood gum precipitated from the black liquor by acidification is believed to be largely lignin and resin-acids, the clear liquor remaining being a sodium sulfate. .solution-assum1ng that sulfuric acid was used for the precipitation.

These ingredients of the wood gum being known, chemical methods already understood may be employed to separate them and to utilize either separately, and for, other purposes than those herein set forth, if desired.

I claim: v I I v 1. A composition of'matter comprising a solid derivative of black liquor adapted to be heat-molded.

2. A molded article of composite ingredients comprising as a principal ingredient a solid derivative of black liquor.

3. A plastic material, comprising a reaction product of analdehyde with black liquor.

L A plastic material, comprising a reaction product of an aldehyde with black liq uor-axid a phenolic body.

5. A molded article comprising a mixture of the product resulting upon acidification of black liquor with a binder.

6. A molded article comprising a mixture of the product resulting upon acidification of black liquor with a condensation product of a phe'nolic body with an aldehyde.

7. A molded articlecomprising a co-condensation product of a black liquor derivative and a phenolic body with an aldehyde.

8. A plastic material comprising a powdcr, being the dried condensation product, of the precipitate thrown down from black liquor by an acid, and an aldehyde.

9. A plastic material comprising a condensation product of'reaction of acetaldehyde with a derivative of black liquor and a phenolic body.

'10. In the manufacture of plastic material, the process which comprises precipitating black liquor with an acid, redissolving the precipitate in alkali solution and adding an aldehyde.

11. In the manufacture of plastic material, the process which comprises precipitating black liquor with an acid, redissolving the precipitate in alkali solution and adding formaldehyde. I

12. Inthe manufacture of plastic material, the process which comprises mixing an alkaline solution of black liquor solids with an aldehyde and a phenolic body and allow ing the mixture to undergo spontaneous reaction.

13. In the manufacture of plastic mate:

rial, the process which comprises mixing an. alkaline solution of black liquor solids with an aldehyde and a phenolic body, allowing the mixture to undergo spontaneous reaction and separating the condensation I formed by acidification ofthe solution.

Signed at Boston, Massachusetts, this thirtieth day of July, 1924.

LESTER o. comma.